Astronomers find evidence of an extragalactic exoplanet

[Peter1469]

Astronomers find evidence of an extragalactic exoplanet

Scientists have found thousands of exoplanets in the Milky Way. Now they find evidence of one in another galaxy.

Since the first detection of the first exoplanet in 1992, astronomers have found thousands of others. Indeed, they estimate that the Milky Way is home to 40 billion worlds.


So it’s easy to imagine that planets must be common in other galaxies, particularly those that seem similar to our own. But when it comes to spotting these planets, there is a problem.


Other galaxies are so far away and the stars crammed into such a small region of space, as seen from Earth, that it is hard to identify individual ones let alone the effects of any planets around them. So extragalactic planets have sadly eluded astronomers.


Now Rosanne Di Stefano at the Harvard-Smithsonian Center for Astrophysics along with several colleagues, say they have found a candidate planet in the M51 Whirlpool Galaxy some 23 million light years from Earth near the constellation of Ursa Major. This alien world, christened M51-ULS-1b, is probably slightly smaller than Saturn and orbits a binary system at a distance of perhaps ten times Earth’s distance from the Sun.


The observation was possible because of a special set of conditions. The planet’s host binary system consists of a neutron star or black hole which is devouring a massive nearby star at a huge rate. The infall of stardust releases huge amounts of energy, making this system one of brightest sources of X-rays in the entire Whirlpool Galaxy. Indeed, its X-ray luminosity is roughly a million times brighter than the entire output of the Sun at all wavelengths.

X-Ray images

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